The following discussion of the prior art is intended to present the invention in an appropriate technical context and allow its significance to be properly appreciated. Unless clearly indicated to the contrary, however, reference to any prior art in this specification should be construed as an admission that such art is widely known or forms part of common general knowledge in the field.
Lorcaserin hydrochloride is an agonist of the 5-HT2c receptor and shows effectiveness at reducing obesity in animal models and humans developed by Arena Pharmaceuticals. It is chemically represented as (R)-8-chloro-1-methyl-2,3,4,5-tetrahydro-1H-3-benzazepine hydrochloride having Formula (I) as depicted herein below.

U.S. Pat. No. 6,953,787 B2 discloses compound of Formula (I) and pharmaceutically acceptable salt, solvates or hydrates thereof and process for preparation thereof.
U.S. Pat. No. 8,168,624 B2 discloses (R)-8-chloro-1-methyl-2,3,4,5-tetrahydro-1H-3-benzazepine hydrochloride hemihydrate and process for its preparation. The patent also discloses crystalline Form I, Form II and Form III of (R)-8-chloro-1-methyl-2,3,4,5-tetrahydro-1H-3-benzazepine hydrochloride. The crystalline Form I and Form II are reported as anhydrous, non-solvated crystal forms. The crystalline Form III displays a dehydration feature calculated as a 3.7% weight loss which is consistent with the theoretical weight loss of 3.7% for a hemihydrate.
The patent discloses that anhydrous Form I and Form II readily converts to a hemihydrate, upon exposure to moisture. The dynamic vapor sorption (DVS) data for each of the three crystal forms reveals the hygroscopic nature of both Forms I and II, which readily adsorb moisture at relative humidity (RH) greater than about 40-60%. In addition, both Forms I and II were calculated to adsorb about 3.8% moisture between about 40 and about 80% RH which is consistent with conversion to the hemihydrate (Form III). X-ray powder diffraction (XRPD) carried out on both Forms I and II after the DVS cycle confirmed this conversion. In contrast, the DVS data in connection with Form III shows that it is substantially non-hygroscopic, adsorbing less than 0.5% water at 90% RH and the XRPD pattern showed no change in crystalline form after the DVS cycle.
International (PCT) Publication Nos. WO 2003/086306 A1, WO 2005/019179 A1, WO 2006/069363 A1, WO 2007/120517 A1, WO 2008/070111 A1 and WO 2009/111004 A1 disclose various synthetic approaches for the preparation of (R)-8-chloro-1-methyl-2,3,4,5-tetrahydro-1H-3-benzazepine, its related salts, enantiomers, crystalline forms and intermediates.
International (PCT) Publication No. WO 2006/071740 A1 discloses combination of (R)-8-chloro-1-methyl-2,3,4,5-tetrahydro-1H-3-benzazepine with other agents.
International (PCT) Publication No. WO 2012/030938 A1 discloses various salts of lorcaserin with optically active acids.
U.S. PG-Pub No. US 2014/0187538 A1 discloses amorphous lorcaserin hydrochloride and amorphous solid dispersion comprising lorcaserin hydrochloride and one or more pharmaceutically acceptable carriers and processes for their preparation.
International (PCT) Publication No. WO 2014/135545 A1 discloses solid dispersion comprising amorphous lorcaserin hydrochloride and one or more pharmaceutically acceptable water soluble polymers.